ANS is committed to advancing, fostering, and promoting the development and application of nuclear sciences and technologies to benefit society.
Explore the many uses for nuclear science and its impact on energy, the environment, healthcare, food, and more.
Division Spotlight
Young Members Group
The Young Members Group works to encourage and enable all young professional members to be actively involved in the efforts and endeavors of the Society at all levels (Professional Divisions, ANS Governance, Local Sections, etc.) as they transition from the role of a student to the role of a professional. It sponsors non-technical workshops and meetings that provide professional development and networking opportunities for young professionals, collaborates with other Divisions and Groups in developing technical and non-technical content for topical and national meetings, encourages its members to participate in the activities of the Groups and Divisions that are closely related to their professional interests as well as in their local sections, introduces young members to the rules and governance structure of the Society, and nominates young professionals for awards and leadership opportunities available to members.
Meeting Spotlight
ANS Student Conference 2025
April 3–5, 2025
Albuquerque, NM|The University of New Mexico
Standards Program
The Standards Committee is responsible for the development and maintenance of voluntary consensus standards that address the design, analysis, and operation of components, systems, and facilities related to the application of nuclear science and technology. Find out What’s New, check out the Standards Store, or Get Involved today!
Latest Magazine Issues
Apr 2025
Jan 2025
Latest Journal Issues
Nuclear Science and Engineering
May 2025
Nuclear Technology
April 2025
Fusion Science and Technology
Latest News
Norway’s Halden reactor takes first step toward decommissioning
The government of Norway has granted the transfer of the Halden research reactor from the Institute for Energy Technology (IFE) to the state agency Norwegian Nuclear Decommissioning (NND). The 25-MWt Halden boiling water reactor operated from 1958 to 2018 and was used in the research of nuclear fuel, reactor internals, plant procedures and monitoring, and human factors.
Nader M. A. Mohamed
Nuclear Science and Engineering | Volume 173 | Number 2 | February 2013 | Pages 172-181
Technical Paper | doi.org/10.13182/NSE11-77
Articles are hosted by Taylor and Francis Online.
Zirconium is studied in this paper as a reflector for light water reactors. An exploratory analysis of using zirconium as a reflector for two simple reactor core models was carried out. The study showed that use of zirconium as a reflector has a valuable impact on the core reactivity. The study also showed that zirconium-water reflector is more effective than water reflector or stainless steel-water reflector. A typical Westinghouse 1150-MW(electric) pressurized water reactor was simulated using the Monte Carlo code MCNP5 as a case study. The simulation was carried out at the beginning of the core cycle of three batch cores with 235U enrichments of 2.25, 2.8, and 3.3 wt%. The simulation showed that use of Zircaloy-4 reflector between the fuel assemblies and the core barrel adds a positive reactivity Δkeff of 0.00686, while use of stainless steel reflector adds a positive reactivity Δkeff of 0.0037.Use of Zircaloy-4 reflector increases the relative power density in the peripheral assemblies by ˜38%. The power peaking factor is shifted from the center toward the periphery, and the assembly power peaking factor is reduced by ˜13%. The use of Zircaloy-4 reflector with this increase of the reactivity of the peripheral assemblies increases the fast neutron current (E > 0.5 MeV) that reaches the reactor pressure vessel (RPV) by 70%, while the use of stainless steel reflector reduces it by 44%.Adjusting the 235U enrichment in the peripheral assemblies batch to compensate for the excess reactivity caused by using Zircaloy-4 reflector reduces the 235U enrichment by 8.5% in this batch. This means a reduction of 3.35% of the core 235U average enrichment can be achieved by the use of Zircaloy-4 reflector. This reduction in the 235U enrichment reduces the increase of the fast neutron current that reaches the RPV to 23%. In this case, increasing the water gap between the core barrel and the RPV by 3 cm reduces the fast neutron current that reaches the RPV to 95% of that of the basic case. The use of Zircaloy-4 reflector has a good effect on flattening the fission density distribution in the peripheral assemblies batch both before and after reducing 235U enrichment.
